Metal casting apparatus



Oct. 24, 1944. R* K HOPKINS. N 2,361,101

` METAL CASTING APPARATUS y Filed NV. 2, 1943 INVENTOR sumed, it is fedendwise with Patented Oct. 24, 1944 METAL CASTING APPARATUS 'RobertrKHopkins,- New York, N. Y., assignor to The M. W.

Kellogg Company,

New York, N. Y.,

a corporation of Delaware Application November 2,1943, Serial No.508,722.0v

l(Cl. 2257) 9 Claims..

. The present invention relates to the art of producing-cast metalbodies.

In the electric fusion method of producing cast metal bodies such asingots, a consumable electrode containing some or all of the metalingredients of the ingot to be produced, has one end submerged in aprotective layer of iiux in a mold. Current discharged through a gapseparating this electrode from the body of deposited molten metalcreates a metal fusing zone, so that said electrode, as well as othermetal ingredients which may be fed in this` zone, are fused anddeposited as molten metal below the flux layer. This electrode passesthrough a, contact sleeve or nozzle which supplies metal fusing currentto the electrode, and which extends into the mold above the iiux layer.-As the electrode is conrespect vto the contact nozzle to maintain aconstant positional relationship between the current discharge end ofthe electrode and the surface of the deposited molten metal. As thelevel of the molten metal in the mold gradually rises, the level of theiiux also rises to the same extent. It is necessary, under theseconditions, to raise the contact nozzle to maintain a predeterminedpositional relationship between the lower end of the nozzle and ltheupper surface of the ux. If the contact nozhot ux layer, the said layermay of the contact nozzle.

When the mold is of comparatively large crosssection, a., pilot controlits lower end will be maintained a constant'predetermined-distance above'the surface of the flux layer.` However, when the cross-section .of themold is small, it is dicult to use the pilot control because 'oi thelimited clearance aiorded by said mold.

One object of the present invention is to provide a new and improvedcontrol means which maintains a constant positional relationship betweenthe contactnozzle and the ux layer in a mold, and which is entirelyoutside the mold cavity.

Various other objects of the invention will be apparent from thefollowing particular description, and from an inspection ofthe-accompanying drawing, which shows somewhat diagrammatically partlyin Vertical section and partly in front elevation a casting apparatushaving nozzle control means embodying the present invention.

Referring to the drawing, there is provided a mold II) which maybe ofany suitable hollow shape in accordance with the desired shape of thecast body toA be produced, but which is shown in the form of an uprightcylindrical tube having an elongated cavity II of comparatively smallcross-section. This mold I is desirably of a metal having high heatconductivity such as copper, and is provided with a jacket I2 for thecirculation of a suitable cooling liquid therethrough. An inletpipe I3for the cooling liquid is shown connected into the upper end of the moldjacket may be employed therein to move automatically the contact nozzle,so thatv .so that current I2. An outlet pipe (not shown) vfor thecooling liquid may be connected to the lower end of this mold jacket I2.

The lower end of the mold I0 may be closed by any suitable means, as forexample a stool (not shown), also of metal such as copper, and alsodesirably hollowed to form a jacket for the circulation of a suitablecooling liquid therethrough.

The metal is produced and deposited in the mold I I! by the use of aiiux submerged electrode v device which may be of the general type shownin my U. S. Patent No. 2,191,479, issued Februaryv 27, 1940. For thatpurpose, there is provided a consumable electrode I4 extending in themold I0. Electrode I4 may be solid and contain al1 of the constituentsof the desired metal I5 or electrode I4 may be hollow and be made ofsome of the constituents of metal I5 while the remainder of theconstituents are supplied through electrode I4 to the -fusion zonecreated at the discharge end of electrode I4 at controlled rates in thefluent form of granules, pellets, powders, and the like., "The rate ofsupply of electrode I4` and the rate of supply of the material in iluentform being adjusted to produce a metal I5 in the mold I0 having vtherequired analysis.

The lower end of the electrode I4 is submerged in a oating layer orblanket I6 of flux of any suitable composition having the properelectrical and/metallurgical characteristics and is spaced above theupper surface of the deposited metal-|5 bya gap I'I.

This i'lux I6 refines the metal as it is produced, promotes `fusion ofthe metal, protects it against atmospheric contamias manganese silicate,calcium silicate, aluminum silicate, glass andthe like.

The electrode I4 and the deposited metal I5 are electrically connectedin the same circuit, as it is discharged from said electrode, passesthrough the gap I1, and theresaid nozzle, but tight enough to maintainelectrical contact between said nozzle and said electrode.

The electrical connection of the deposited metal I5 into the circuit ofthe contact nozzle to permit the feeding of said electrode through ing35 in the mold jacket I2. This contact housing 35 is in slide engagementwith the outer surface of the inner metal mold wall 36, and thethermo-sensitive element therein is in slide contact with this surface,or at least in close proximity thereto to react thermally'l upon changesin temperature in the mold cavity I I at the level of said element.

`The control device is advantageously of the' thermocouple type, so thatthe thermo-sensitive element in the contact shoe 35 would be the hot fjunction or couple of the device, although as far I8 may be e'ected asfor example, by grounding the metal walls of the mold I0.

The contact nozzle I8 serves not only as a means of maintaining a steadycurrent feed to the electrode I4, but also serves as a feed guide forsaid electrode. The lower end of this contact nozzle I8 is-spaced asubstantial distance above the upper level lof the ux I6 to prevent saidnozzle from being destroyed by the intense heat of the superheated fluxI8.

As the metal producing operation progresses,

the level of the deposited metal I5 as well as that ofthe flux layer I6gradually rises. As the electrode I4 is consumed and the deposited metalI5 rises, said electrode is moved at a rate necessary to maintain thecurrent discharge gap I1 constantin length. 'Ihis controlled movement ofthe electrode I4 may be effected in any wellknown manner, as for examplethrough a pair of feed wheels 20 on opposite sides of the electrode I4and in frictional engagement therelwith. At least one of these feedwheels 2li is driven from a motor 22 through a suitable reductiongearing, while the other wheel may be positively driven from said motoror may be merely an idler.

` Motor 22 may be controlled, for example, by the voltage drop acrossthe gap I1 in any well-known manner,` as is common in the. electric arcwelding and electric arc furnace arts, so that the feed wheels 20 areautomatically operated and controlled to feed the electrode I4 asnecessary to maintain a discharge gap I1 of constant length.

As the level of the flux I6 gradually rises, it is necessary to move thecontact nozzle I8 upwardly to an extent necessary to maintain a constantpositional relationship between the lower end of said contact nozzle andsaid flux layer. For moving the contact nozzle I8 upwardly, said nozzleis secured to a hoist 23 by.

any suitable means, as for examplethrough a clamp 24. This hoist 23maybe moved verti:`

cally by any suitable means. Thus, hoist 23 may be moved in the mannerindicated in the drawing through a pair of vertical 'feed screws 28jthreaded therein, and journalled in suitable fixed bearings 21 arrangedto hold these feed screws against .axial movement. The two feed screws26 are driven in unison and in the same direction through a motor 28 anda speed reducing transmission between said motor and said feed screws.`This transmission, for example, may comprise worm wheels 30 keyed orotherwise af'- iixed to feed screws respectively for rotation therewith,and meshing with respective'worm wheels onthe shaft ofthe motor 28.

'As a-feature of the present invention, the op eration of the motor 28is automatically controlled by means of a thermo-responsive controldevice .disposed entirely outside of the mold cavity II. This controldevice is desirably of the electric pyrometric type having' a heatsensitive element enclosed in. a contact shoe or houstive element in thecontact shoe would be the resistance element of the device.

Connected to the contact shoe 35 is a conduit 38 through which the leads31 from the thermocouple or junction extend. These leads 31 are sealedand insulated from the cooling liquid in the mold jacket I2, and connectinto a control unit 39. This control unit 38 may be of any well-knowntype, in which the generatedthermoelectric current when increased instrength above a predetermined value, closes a switch (not shown) in thecircuit of the hoist motor 28 and thereby operates said motor, and whenit falls below a predetermined value opens this switch and therebyshutsoi said motor. The motor 28 for that purpose is connected to thiscontrol unit 39 by the leads 40.

Contact shoe 35 is positioned to maintain the bottom end of contactnozzle I8 the chosen distance above the Atop surface of the hot flux orslag I6. In operation, since the volume of metal as shown, the intenseheat of the ilux is trans,-`

mitted to the thermocouple through the metal mold wall 36. This resultsin the generation of thermo-electric current above a predeterminedvalue, and the consequent closing of of the motor 28. The motor 28 willtherefore rotate in a direction to raise the hoist 23 through the feedscrews 26 so that the contact nozzle I8 is raised. At the same time, thecontact shoe 35 is raised in unison with the contact nozzle I8, so thatwhen said contact shoe reaches that positionabove the intense heatedarea defined by the flux I6, at which the generated thermo-electriccurrent falls below a predetermined. value, the motor 28 shuts down.

For eiecting Athe movement of vthe contact shoe By means of theconstruction described, the

lower end of the contact nozzle I8 is maintained at a constantpositionalrelationship with respect to the flux I6, soA that at no time will thiscontact nozzle become overheatedv or will it in any way dip` into saidux. y

The feed device 20 and 22 for the electrode I4 may, if desired, besupported on the hoist 23 as shown. With this construction, theelectrodeI4 will be moved upwardly with` the contact nozzle I8, but will still besubject to the control of the .Circuit tion with a control l nozzle I8relative to the flux.

lrent discharge electrode of said contact nozzle layer of ilux,

feed wheels 20 according to the voltage drop across the gap I1, oraccording to any other regulating factor selected, so that the length ofthis gap will be kept substantially constant.

Although the invention is shown in conjuncby which the contact nozzle I8 and the thermocouple conduit 36 are raised from a stationary mold Iwhile the casting operation progresses,

35 may be kept stationary, while the mold I0 is lowered by some controldevice similar to that shown to maintain a constant positionalrelationship between the contact nozzle I8 and the ux I 6.

Also, in accordance with certain aspects of the present invention,instead of controlling the motor 28 by alternately turning it ofi'` andon, said motor can be regulated by controlling its speed to ymaintainthe desired .position of the contact may be of the reversible type topermit the hoist 23 to be lowered for each new casting operation.

The reversing circuit for this motor 28 may be of anwtlfpe-Well-known inthe art.

As many changes can be made in the above apparatus, -and many apparentlywidely diierent embodiments of this invention can be made withoutdeparting from the scope of the claims, it is intended that all mattercontained in the above description or shown in the accompanying drawingshall be interpreted as illustrative and not in a limiting sense. o.

What is claimed is:

1. A casting apparatus comprising a mold with a metal wall confining themold cavity, a curadaptedy to extend into said mold with its lower endsubmerged in a layer of ux, a contact nozzle for said electrode adaptedto extend into said mold above said ux,

a thermo-responsive element on the outside of said mold cavity adjacentto said wall, and means for translating the action of heat ofpredetermined intensity on said element into a corresponding motiveforce, whereby axial movement relative to said mold can be controlled inaccordance with said force to maintain said nozzle a substantiallyconstant distance above said ilux.

2. A casting apparatus comprising a mold with a metal wall confining themold cavity, a current discharge electrode adapted Ato extend into saidmold with its lower end submerged in a a contact nozzle for saidelectrode adapted to extend into said mold above said as far as certainaspects of the linvention are concerned, the contact nozzle I 8` as wellas the conduit 38 with its contact shoe I6. This motor 28 A nozzle. andmeans responsive to the thermal reaction of the flux on said element forcontrolling the operation of said motor.

4. A casting apparatus comprising a mold with a metal wall confining themold cavity, a current discharge electrode adapted to extend into saidmold with its lower end submerged in a layer of ux, a contact nozzle toextend into said mold above said flux, a thermo-'responsive elementonthe outside of said mold cavity adjacent to said wall, means fortranslating the action of heat of predetermined intensity on motiveforce, contact nozzle whereby axialvmovement of said relative to saidmold can be controlled in accordance with said force to main'- ing saidnozzle and said thermo-responsive element for movement in unisonrelative to said mold.

5. A casting apparatus comprising a mold with a metal wall conining themold cavity, acurrent discharge electrode adapted to extend into saidmold with its lower end submerged in'a layer of ux, a contact nozzle forsaid electrode adapted to` extend into said mold above said ux, control.means for automatically maintaining constant the positionalrelationship between said contact nozzle and the ilux in said mold, saidcontrol means comprising a thermo-responsive element on the outside ci?asaid cavity adjacent to said wall, a motor for'causing relative axialmovement between' said mold and said contact nozzle, and meansresponsive to the thermal reaction of the flux on said element forcontrolling the operation of said motor, and means interconnecting saidthermo-responsive element and proximity said contact nozzle for ative tosaid mold.

6. A casting apparatus comprising a mold with a metal wall confining themold cavity, a current discharge electrode adapted to extend into saidmold with its lower end submerged in a layer of nozzle for saidelectrode adapted to extend into said mold above said iux. a shoe inslide contact with the outersurface of said wall, a thermo-responsiveelement in said shoe in close to said wall to react readily when the uxreaches a position near the level of said element, means for translatingthe action of heatl of predetermined intensity on said element into acorresponding motive force, whereby axialy movement of said contactnozzle relative to said ux, and thermometric control means forautomatically maintaining substantially constant the positionalrelationship between said contact noz- -zle and the ux in said mold,said control means comprising a thermo-responsive element on the outsideof said mold cavity adjacent to said wall.

3. A casting apparatus comprising a mold with a metal Wall conning themold cavity, a current discharge electrode adapted to extend into saidmold with its lower end submerged in a layer of ilux,a contact nozzlefor said electrode adapted to extend into said mold above said flux, andcontrol means for automatically maintaining constant the positionalrelationship between said contact nozzle and the ux in said mold, saidcontrol means comprising a thermo-responsive element on the outside ofsaid cavity adjacent mold can be controlled in accordance with saidforce to maintain said nozzle a; substantially constant distance abovesaid ilux, and means interconnecting said nozzle and said shoe formovement -in unison relative to said mold.

7. A casting apparatus comprising a mold with a metal wall confining themold cavity, a current for causing relative axial movement mold and saidcontact nozzle, and means refor said electrode adapted said element intoa corresponding movement in unison relsponsive to the thermal reactionof the ux on said element for controlling the operation of said motor,and means interconnecting said shoe and said nozzlefor movement inunison relative to said mold.

8. A casting apparatus comprising a mold with an inner metal wall and anouter wall'forming therebetween a jacket for the circulation of acooling liquid therethrough, a current discharge electrode adapted toextend into said mold ,with its lower end submerged in a layer of flux,a contact nozzle for said electrode adapted to extend into said moldabove said flux, and control means for automatically maintainingconstant the positional relationship between said contact nozzle and theflux in said mold, said control means comprising Va thermo-responsiveelement in said jacket adjacent to said inner wall, a motor for causingrelative axial movement between said mold and said contact nozzle, andmeans responsive to the thermal reaction of the ilux on said element forcontrolling the operation of said motor.

9. An apparatus for producing ingots comprising a mold, an inner metalwall and an outer wall forming therebetween a jacket for the circulationof a cooling liquid therethrough, a current discharge consumableelectrode adapted to extend into said mold with its lower end submergedin a layer of ux, a contact nozzle for said electrode adapted to extendinto said mold above said ux,- thermocouple control means forautomatically maintaining constant the positional relationship betweensaid contact nozzle and the flux in said mold, said control meanscomprisingv in a direction to raise said nozzle, and meansinterconnecting said nozzle and said shoe for controlled movement inunison.

ROBERT K. HPKms.

